Oil leak again

robsad

robsad

True Classic
I had a fairly large oil leak in the rear of the engine so that after a run I would have a 6 inch across puddle centered around the forward corner of the oil pan nearest the fuel tank where the oilpan tucks under the crossmember. So I replaced the oilpan gasket with the thicker composite type from MWB with a thin coating of Blue Hylomar on both sides of the gasket. I waited overnight before I restarted it. This did nothing to fix the leak. I know it's engine oil because I did the UV dye test. At rest it's a drip but when engine is running the drip becomes a stream. It seems to come from the area where the trans joins the engine. I did check the oilpan for warping and found nothing. I did not over tighten the oilpan bolts. In fact there are places where this thick gasket squeezed out a bit but that's not where the leak seems to be coming from. I don't believe it's the rear main seal either. My mistake was I should have left the crossmember off so I could better see the area when I restarted the engine. Can anyone chime in with any ideas or experiences with leaks in this area ? Thanks in advance,

Bob
 
robsad said:
I don't believe it's the rear main seal either.
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Bob, I'm curious why you do not think it is the rear main seal? From what you've said it sort of sounds like it to me.

All of my X's had leaking rear main seals to some degree when I got them. One was bad and the seal looked to be very old despite all of the other seals looking brand new. I suspect a prior owner managed to replace the others with the engine in the car, but could not access the rear one that way (flywheel must come off). The new front seal was also leaking a little. When I removed it I found the aluminum front cover had been broken (into chunks) on the inside from driving the new seal in too aggressively/deeply. Unfortunately bits of that aluminum destroyed other internal components.

To find the source of your leak, clean everything thoroughly with brake cleaner. Go for a drive. Put the rear up on stands and drop the crossmember with the jack supporting the trans/engine. Your dye should show an obvious fresh trail from the source.
 
Adding to what Dr. Jeff said, when you get the crossmember off, you might get a better view by removing the sheet metal cover on the lower bellhousing.

Normally, the thick pan gasket is used for the sheet metal pan (128) and the thin gasket is used for the alloy pan (X1/9). If you are using the thick gasket with the alloy pan, you need to make sure it is tightened very evenly and carefully so that the pan does not get distorted. However, if that joint is well covered with blue Hylomar, I would think the problem is elsewhere. The rear seal is a likely candidate but it also might be worth checking the oil pressure senders. Perhaps the idiot light sender on the head is managing to leak down that way.
 
The main oil gallery plug in the rear is just above and forward of the rear main. If this is leaking you would get a lot of oil on the floor. Of course it could be the head gasket (they tend to leak to the front of the engine), or even the cam carrier to head joint. But, most likely candidate, as mentioned above is the rear main seal.
 
I should have added - this is a freshly rebuilt motor. I guess I'm looking for the simplest solution. Probably wishful thinking. I was very meticulous about rebuilding the bottom end but I didn't think about the gallery plug. All the plugs were new and installed with the correct sealants as we're the new main seals. I will take the cross member and bottom shield off and retest. Thanks to all for replying. I'll do an update in the next few days.
 
robsad said:
I should have added - this is a freshly rebuilt motor.
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Ahhh, now I see where you are coming from. I suppose it isn't impossible for a new seal to not seal. The suggestion about the oil pressure sender/switch is a good one. Way back when the VW Beetle with a air cooled engine was popular the oil pressure sender was a common source of leaks for some reason. Oil goes right past the electrical terminal on it. But all of the other suggestions are also good. So guess you will have to do some investigating. Please let us know what you see.
 
Jeff et al,
Just took off the crossmember and lower trans shield, cleaned the leaking area again and started the engine (with UV dye still in). It's not any of the senders or top end gaskets. Its leaking right where the bell housing meets the engine on the lower left side right by the corner of the oilpan. If its the rear main seal or gallery plug wouldn't it be puddling inside the bellhousing and then leaking out of more than one specific place ? I snugged the oilpan bolts where needed so I'm almost positive it's not the oilpan gasket. Also there is no oil anywhere on the flywheel. I would think if it was the rear main seal there would be oil on the side of the flywheel that faces the block but there is no sign of it. And this UV dye REALLY shows up florescent yellow/green so that side of the flywheel is clean and dry. I guess the only thing to do now is pull the trans and really see what's going on. I almost hope that I find something - this will be the second time I've pulled the trans this summer. I pray this will be the last time I have to do this.

Bob
 
Was there a reason you used the thick pan gasket? I've only heard it used with an alloy pan as a desperation measure to seal one that is warped.
 
robsad said:
I would think if it was the rear main seal there would be oil on the side of the flywheel that faces the block but there is no sign of it.
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Bob I agree, that does not sound like the rear main seal.
The oil galley plug is a little higher and off toward the left side. A leak from there might possibly run down the edge of the block to the lower corner, but you should see the trail. Although the bell housing may be covering it so you can't see it.
Also the aluminum rear cover that holds the rear main seal joints at that corner with the block and oil pan. Perhaps an issue with the aluminum cover? As mentioned, I have one that had broken internally (front cover but same concept).
I understand where Don is coming from about the thicker pan gasket, but I doubt that would create a leak. Usually it is more of a potential fix for an existing leak. It sounds like you installed it correctly. One of my engines has had that thick gasket on the pan for decades and never a leak.
I suppose there could be very unlikely things like a crack or such.
Unfortunately the trans might have to come off to see for sure. Maybe let it sit a couple days with the crossmember off and look for traces again, before pulling the trans. Any leaking trails may become more evident. Or let it run longer till things get fully to temp and see if it becomes more obvious.
Hopefully other members more clever than me will have better thoughts to add.
 
Dr.Jeff said:
Bob I agree, that does not sound like the rear main seal.
The oil galley plug is a little higher and off toward the left side. A leak from there might possibly run down the edge of the block to the lower corner, but you should see the trail. Although the bell housing may be covering it so you can't see it.
Also the aluminum rear cover that holds the rear main seal joints at that corner with the block and oil pan. Perhaps an issue with the aluminum cover? As mentioned, I have one that had broken internally (front cover but same concept).
I understand where Don is coming from about the thicker pan gasket, but I doubt that would create a leak. Usually it is more of a potential fix for an existing leak. It sounds like you installed it correctly. One of my engines has had that thick gasket on the pan for decades and never a leak.
I suppose there could be very unlikely things like a crack or such.
Unfortunately the trans might have to come off to see for sure. Maybe let it sit a couple days with the crossmember off and look for traces again, before pulling the trans. Any leaking trails may become more evident. Or let it run longer till things get fully to temp and see if it becomes more obvious.
Hopefully other members more clever than me will have better thoughts to add.
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Jeff,
I originally used the paper oilpan gasket that came with the gasket set. During the breakin period for this rebuilt engine there was a slight drip from the area in question that became worse so I replaced the thin paper gasket with the thick gasket but the drip now is a steady stream while running as if it's under pressure. It does not leak much when not running. It's time to remove the trans and see what's going on. Now that I think about it this engine leaked at that area before I did the rebuild so there might be a crack in the block somewhere ? Wish me luck . . .

Bob
 
Steady stream that is worse when the engine is running implies a leak from a point that is pressurised by the pump... only spot at the left rear of the block is the main oil gallery plug about a third of the way up the block... (when it gets warmer I'll venture out to the workshop and take a picture) never seen one leak that was factory fitted.

SteveC
 
robsad said:
so there might be a crack in the block somewhere ?
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Lets certainly hope not. If it leaks more when it is running, were you able to look with the crossmember off and the engine running? Or if you can safely do it, look with the engine running after you remove the trans (assuming the leak isn't obvious at that point). As unlikely as it might be, that galley plug is in about the right location and is under pressure when the engine runs like Steve said, so it's worth checking. I don't believe there is a way to see it with the trans/bellhousing in place though. But I'd prefer that to be the source than a crack.
 
oil gallery plug that is probably leaking....

20190820_150948_LI.jpg


it will be behind the tinware too, and needs the flywheel off to get to it... if it is the issue you might be best removing the engine so you have good access.

You need to be mindful that the plug can be driven in too deep (or screwed in too deep if the hole is threaded for a hex plug) and will block / partially block the feed to the rear main if it is too deep.

SteveC
 
Might this leak be between the pan and the place where the rear gasket from the aluminum rear cover (that carries the rear seal) join? You might solve this with copious amount of RTV at that joint and a new pan gasket.;)
 
Peter Bruecken said:
Might this leak be between the pan and the place where the rear gasket from the aluminum rear cover (that carries the rear seal) join?
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That is one of the places I was trying to describe earlier. I'll use Steve's picture to help point out the location (red/white arrow):

20190820_150948_LI.jpg
 
Dr.Jeff said:
That is one of the places I was trying to describe earlier. I'll use Steve's picture to help point out the location (red/white arrow):

View attachment 24422
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Jeff,
You might be on to something. If you note the large dowel locating pin to the left of your red and white arrow - the edge directly below that dowel pin is where the stream of oil is dripping from. Also there is the large shield there that is sandwiched between the block and trans. About the gallery plug - I was very careful to only sink it flush with the block surface and used either Permatex High Temp sealant or was it Loctite high temp - I can't remember but anyway I'd be surprised if it was that gallery plug. If there was no gallery plug there then the flow of oil would be extreme.
 
Trouble is if I remove the trans and bell housing then I lose the starter so then I can't start it to check for leaks while its running.
 
robsad said:
Trouble is if I remove the trans and bell housing then I lose the starter so then I can't start it to check for leaks while its running.
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I took an extra oil pump / distributor drive and machined (or ground) off the teeth, and pinned on a shaft so I could spin it with a drill through the distributor positioning hole to build oil pressure. You can do this with the transmission off. I am not home now but could take a picture next week.

Paul
 
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